Cracking the H.264 Codec looks at a few H.264 codecs available, each with different configurable parameters, but mostly encoding tools with different sets of compression options.So Many H.264 Codecs, So Little Time compares H.264 files produced using codecs from Apple, Dicas, and MainConcept (the last is licensed by Adobe). Ozer didn't use Visual Hub (Mac, $23), which Andy Beach found to be faster and yield a bit better results at default settings than the other apps he tested in a recent comparison (later expanded and updated) at Real World Video Compression.
As mentioned earlier in Flash H.264 fast start, fees, MSU also compared H.264 codec quality (MainConcept beat other participants). You have to dig to find practicals, so if you're interested in quality Fabio Sonnati has pushed Flash to the limit with low data rates,
"I use a mix of Ffmpeg, x264, Mencoder and Nero AAC. Here some parameters used: 5 reference frames, 5 B-frames, authomatic B-Frames, B-pyramid enabled, adaptive macroblock type, advanced Trellis on, Subq=7, advanced exagon search, deblocking filter with custom alpha e beta parameter, three pass encoding..."
Also, Adobe engineer Tinic Uro's post and comments on H.264 has many interesting details on Flash and MP4.
On a side note, in Optimal frame dimensions for Flash video, Adobe is now saying that h.264 (encoding or playback) is optimized for 16x16 samples, rather than 4 or 8. Adobe also posted a Flash video bitrate calculator by Robert Reinhardt. Looking through papers on the web (H.264/MPEG-4 AVC from Wikipedia or IEEE Overview of the H.264/AVC is a start) it’s hard to tell if 16x16 is really best -- it seems to be rather how the encoder is implemented (in chroma sampling for example). Anyway if 16x16 is optimal, presets for the various Adobe applications should reflect this -- though they don't so far.
Update: in a new article (8/25/08) Ken Stone talks about how to get decent QuickTime H.264 movies from FCP for the Web and similar companion article (9/8/08) Compressor H.264 movies from FCP for the Web.
Jan Ozer also has a video tutorial that shows the new features in Rhozet's Carbon Coder 3.0, including the Carbon Administrator, which now contains the Queue Manager and the enhanced watch folder functions.